Modern circuits (such as integrated circuits (ICs)) are enormously complicated. For example, an average desktop computer chip can have over 1 billion transistors. Due to the complexity and high cost, IC design is often outsourced to a third party that completes the circuit design by using hardware that incorporates software (such as Electronic design automation (EDA) or Computer Aided Design (CAD) tools). Such outsourcing provides opportunities for attackers to take over the designed IC by introducing malicious alterations or hardware Trojans (HTs), which causes serious security concerns especially for security-critical applications such as military applications. A HT can cause malfunction for a circuit into which the HT is embedded or destroy a system incorporating such circuit, lower circuit reliability and leak confidential information.
New methods and apparatus that assist in advancing technological and security needs and industrial applications in circuit technology, IC design, verification, and fabrication processes are desirable.
In addition, in designing very large-scale integration (VLSI) circuits, the function of the IC may have to be changed some time after its initial design for various reasons such as to improve its performance, to introduce new features or to mask HT. Such change is generally implemented by performing engineering change orders (ECO). However, existing ECO techniques are slow and inefficient. Therefore, new methods and apparatus for transforming the function of an IC is desired.